In general, digitizers convert images on various media to an electric signal which can then be stored, transferred, or analyzed in any number of ways. The image captured on the media can be described by a two-dimensional array of picture elements or pixels quantified in terms of the transmittance or optical density of the medium at the particular coordinates of the pixels.
A medium that has regions of high optical density (low transmittance) and low optical density (high transmittance) requires a digitizer capable of accurately reading such image data. Some media, e.g., transparent media such as X-ray films, have images with such a wide range of optical densities. One way of measuring the performance of a digitizer system to capture such a wide range of image data is its dynamic range. Dynamic range is generally defined as the ratio of the maximum output signal of a light detector of the digitizer when illuminated with light and the noise output in the absence of light. It is typically expressed as the Log (White signal/RMS noise). Any reduction in noise would therefore serve to effectively increase the dynamic range of the digitizer.
Accordingly, there is a need in the art for a digitizer capable of reducing noise and therefore improving dynamic range, as well as increasing the photometric resolution of a digitized image.